The present invention relates to improvements to gas burners, particularly for household appliances such as cookers or cooking plates, comprising a burner body having a peripheral side wall with flame orifices distributed circumferentially, this peripheral wall being further formed so as to define at least one outwardly open enclosure into which opens at least one supply orifice whose cross section is such that it ensures a flow speed of the combustible air-gas mixture equal or close to the flow speed through the other flame orifices, the volume of this enclosure being such that it allows expansion of the gas mixture so that the pressure inside the enclosure is equal or close to the static pressure and the cross section of the outlet opening of this enclosure being such that the flow speed of the gas mixture which passes through it is from about 7 to 12 times less than the speed of the gas flow through the flame orifices.
It is known that sudden pressure variations of the primary air fed into a gas burner for being mixed therein with the combustible gas may cause the flames of the burner to disappear during slow running.
It has already been proposed (U.S. Pat. No. 4,757,801) to overcome this drawback by providing, at the level of the peripheral wall of the burner body which is provided with the flame orifices, an outwardly open enclosure into which opens at least one supply orifice whose cross section is such that it ensures a flow speed of the airgas fuel mixture equal or close to the flow speed through the other flame orifices, the volume of this enclosure being such that it allows expansion of the gas mixture so that the pressure inside the enclosure is equal or close to the static pressure and the cross section of the outlet opening of this enclosure being such that the flow speed of the gas mixture which passes through it is from about 7 to 12 times less than the speed of the flow speed feeding the flame orifices.
Such an arrangement is quite satisfactory when the pressure variation of the primary air remains at a relatively moderate value, being due for example to the sudden opening or closing of the door of the oven of a cooker embedded between other furniture or else to a draught of average violence.
On the other hand, this arrangement is inefficient when the pressure variation of the primary air is very sudden and very considerable, being due for example to a very violent draught sweeping over the burner or else to the cumulation of a draught and a pressure jump caused by closing or opening the door of the oven.